Inhibitory role of phosphatidylinositol 4,5‐bisphosphate on TMEM16A ‐encoded calcium‐activated chloride channels in rat pulmonary artery

作者：Harry A. T. Pritchard, Normand Leblanc, Anthony P. Albert, Iain A. Greenwood · 发表于：British Journal of Pharmacology · 年份：2014 · DOI：10.1111/bph.12778 · 被引用次数：60 · 研究领域：Ion channel regulation and function、Ion Channels and Receptors、Protein Kinase Regulation and GTPase Signaling

BACKGROUND AND PURPOSE: Calcium-activated chloride channels (CaCCs) are key depolarizing mechanisms that have an important role in vascular smooth muscle contraction. Here, we investigated whether these channels are regulated by phosphatidylinositol (4,5) bisphosphate [P(4,5)P2 ], a known regulator of various ion channels. EXPERIMENTAL APPROACH: Calcium-activated Cl(-) currents (IClCa ) were recorded by patch clamp electrophysiology of rat isolated pulmonary artery smooth muscle cells. TMEM16A protein-phosphoinositide interaction was studied by co-immunoprecipitation and phosphoinositide binding arrays on protein lysates from whole pulmonary arteries and HEK293 cells overexpressing TMEM16A, the molecular correlate. KEY RESULTS: PI(4,5)P2 and other phospholipids were shown to bind directly to TMEM16A isolated from whole pulmonary artery (PA) and TMEM16A-eGFP expressed in HEK293 cells. Agents that reduced PI(4,5)P2 levels through different routes [PLC activation, PI4K inhibition, PI(4,5)P2 scavenging and absorption] all increased IClCa evoked by solutions containing clamped-free [Ca(2+) ], whereas enrichment of activating solutions with PI(4,5)P2 inhibited IClca in PA smooth muscle cells with approximately 50% reduction at 1 μM. CONCLUSIONS AND IMPLICATIONS: These data are the first to show a negative regulation of TMEM16A-encoded CaCCs by PI(4,5)P2 and propose that control of PI(4,5)P2 levels is a key determinant of arterial physiology.